chore: import upstream snapshot with attribution

docs/status.md

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+---
+summary: "Provider status checks, sources, and indicator mapping."
+read_when:
+  - Changing status sources or status UI
+  - Debugging status polling or incident parsing
+---
+
+# Status checks
+
+## Sources
+- OpenAI + Claude + Cursor + Factory + Copilot: Statuspage.io `api/v2/status.json`.
+- Gemini + Antigravity: Google Workspace incidents feed for the Gemini product.
+
+## Behavior
+- Toggle: Settings → Advanced → “Check provider status”.
+- `UsageStore` polls status and stores `ProviderStatus` for indicator/description.
+- Menu shows incident summary + freshness; icon overlays indicator.
+
+## Workspace incidents
+- Feed: `https://www.google.com/appsstatus/dashboard/incidents.json`.
+- Uses the Gemini product ID from provider metadata.
+- Chooses the most severe active incident for the provider.
+
+## Links
+- If `statusPageURL` is set, status polling uses it and the menu action opens it.
+- If only `statusLinkURL` exists, the menu action opens it without polling.
+
+See also: `docs/providers.md`.